Recently dental amalgams of high Cu concentration have excited clinical and commercial interest. Claims made for these amalgams include higher marginal strengths and greater corrosion resistance. It will be the purpose of this investigation to analyze the role of copper in affecting the reaction of Ag3Sn-Hg with specific reference to the degree it affects the amount, morphology and distribution of the silver mercury and tin-mercury reaction products. From such analysis it is hoped that an optimum alloy concentration may be adopted to maximize both physical and electrochemical properties of dental amalgam. High Cu concentration amalgams will be fabricated from An3Sn alloy with high Cu concentrations as well as through admixing Ag3Sn with a high Cu concentration second phase. Microstructural and ultrastructural investigations of resulting amalgams which have acceptable handling characteristics will be established as well as biocompatibility studies of promising systems. Appropriate electrochemical and physical property measurements will complete the profile of potentially clinically useful high concentration Cu alloys.